Telephone system



Feb. 17, 1931. R E HERSEY 1,792,538

TELEPHONE SYSTEM Filed June 9, 1928 4'zzz *I /NVEA/mf? RALPHEHERSEY ATTORNEY Patented eb. 17, 1931 UNETZD STATES TELEPHONE SYSTEM Application led J'une 9, 1928. Serial No. 284,207.

This invention relates to telephone systems and has for its object to facilitate the super vision of the service supplied by a group of instrumentalities.

More speciiically the invention relates to means for giving an alarm whenever more than a certain number of demands have been made on a particular group of instrumentalities and remain unsatisfied, together with means'to change the critical number when desired.

This invention has been specifically embodied in connection with the equipment provided at a panel machine switching office whereby an incoming or B7 operator may complete connections incoming` from manual offices. Such an arrangement is disclosed in Patent No. 1,753,348, issued April 8, 1930, to J. B. Newsom. It comprises trunks incoming from a manual office which terminate in selectors, and link circuits which connect with the incoming trunk, find an idle operator and an idle sender and associate them in the proper sequence. During busy hours or during the night when the operating force is reduced, the calls may come in more rapidly than the operators can attend to them, at which time the links associated therewith will be arrested waiting for an idle operator. If such a condition arises often it is desirable to detect it in order that additional operators positions may be placed in service for maintaining adequate service. To accomp'lsli this, whenever a link is waiting for an idle operator, battery through a high resistance is connected to a lead extending to the arrangement of the present invention. This arrangement comprises a marginal relay and an interrupter for completing t-he circuit o-f the relay at predetermined intervals. The marginal relay is so adjusted that it will operate only if a predetermined number of link circuits are waiting for an operator. Since such a condition may occur momentarily without indicating slow service, this marginal relay controls a second relay through another interrupter which closes its contact at half minute intervals. If the condition continues so as to operate this other relay, an alarm is sounded to call attention t0 the fact that the service is inadequate. .By means of a key, a resistance may be connected in parallel with the winding of the marginal relay thus increasing the critical number of waiting links. In addition, if all of the operators positions are busy the circuit of the position finder switch of each waiting link `wililll be held open until a position becomes i e.

The object of the invention will be more clearly understood from a consideration of the following description in connection with the drawing, which shows portions of a number of link circuits and position equipments together with the equipment forming the subject of the invention.

As set forth in the above mentioned patent to J. B. Newsom when a call is to be extended to a subscriber in a dial oce under the control of a B operator at that oce, the seizure of a trunk by an operator at the manual oce initiates the operation of a link circuit at the dial office and causes the advance of the link circuit sequence switch from position 1 to po sition2. In position 2 the trunk finder of the link is operated to connect the link with the trunk which has been seized, and the finding of the trunk advances the sequence switch to position 3. In both positions 2 and 3 circuits are provided for hunting for and seizing an idle operators position and the finding of the position advances the sequence switch to position t and connects the position equi-pment with the trunk. Subsequently, an idle sender is associated with the link, the sender is set under the control of the position equipment, the position equipment is disconnected from the link, and the sender controls the selector in which the trunk terminates and a final selector to select the wanted line. As soon as the line has been found the link and sender are disconnected from the trunk and the connection is placed under the control of the operator at the manual oiiice.

eferring now more particularly to the drawing, there is shown portions of link circuits A, B, C, D, E, and F. There are also shown portions of two operators7 postions M and N and the common equipment for carrying out the present invention. The numerals employed on the drawing are the same as employed in the above identified Newsom patent with the addition ot letter sufliXes where the same apparatus is shown as it occurs in ditferent link or position circuits. The numbers applied to common apparatus below the broken lines apply only to the present disclosure.

Referring tirst to link A, when the sequence switch 400 arrives in position 2, a circuit is closed from ground, over the contact oi cam 32, left back contact ot relay 514, winding ot' relay 513 to battery. Relay 513 in operating closes a circuit from battery, through the winding of relay 507, back contact of magnet 508, upper contact ot cam 434, lett front contact of relay 513, right back `Contact o'j relay 514, lett back Contact of relay 509 to ground. Relay 507 operates closing a circuit from battery, through the winding ot magnet 508, lett front contact of relay 507, lower contact of cam 434, lett front contact of relay 513, right back contact of relay 514, left back contact of relay 509 to ground. Magnet 508 operates in this circuit in turn opening the circuit of relay 507 and relay 507 and magnet 508 operate and release, advancing switch 500 from position to position until an idle operators position is found.

Vhen a position such as position M is occupied as indicated by the insertion of the telephone plug in the jack of the position, a circuit is closed from ground over the. right winding of repeating coil 609-M, jack (505-BL plug 606-M, through the receiver of the head set 600-M, plug G07-M, Qlack 608-M, winding of relay S04- M to battery. Relay 604M when operated connects battery over its inner contact, the inner left back contact ot relay 602M, resistance G01-BL to the corresponding terminal in the bank served by brush 503. Wlhen the position is Vacant this battery is removed from the ter minal by the unoperated condition of relay (S04-M. Similarly, if the position is busy the operation of relay 602-M will open this circuit and disconnect the battery.

In order to test for an idle position, relay 513 closes one circuit and prepares a. second. T he lirst circuit may be traced from battery through the middle winding of relay 514, contacts ot cam 452, lett winding` of relay 514. right front contact of relay 513, contact ot cam 432 to ground. Relay 514 does not operate in this circuit but is rendered quick to operate when the test circuit is closed. The second or test circuit extends from ground over cam 432, right front contact of relay 513. left winding of relay 514, right winding of relay 514, lower contact of cam 433 to brush 503. Vhen brush 503 encounters battery indicating an idle position, this test circuit is completed and relay 514 operates, locking through its middle winding and right front contact to ground at the left back contact of relay 509. It also connects ground through its right winding to brush 503, lowering the potential of the terminal of brush 503 so as to mark the position busy to any other posi tion linders which may be hunting at the time. Relay 514 in operating closes a circuit trom battery, through the winding of relay 437, lett front contact of relay 514, contact of cam 432 to ground. Relay 437 operates and closes a circuit from ground, through the winding ot relay 438, lett contacts of relay 437, brush 505 to the terminal corresponding to position M, winding of relay 610-M to battery. Relay 438 is marginal and does not operate but relay GHF-lil does operate completing a circuit .from battery, over the inner contact of relay 604M, front contact of relay 610M, winding of relay 602-M to the terminal ot brush 504.

Relay 437 also. closes a circuit from battery, through the winding of sequence switch magnet 400, right front contact 01"' relay 437, to ground over cam 408, advancing sequence switch 400 to position 4. As soon as sequence switch 400 reaches position 3%, the circuit above traced for relay (502#M is completed at the Contact oi" cam 440 and relay SO2-M operates disconnecting battery from the terminal ot brush 503. Relay 437 alsok connects the operators telephone to the trunk over circuits not shown.

l.While sequence switch 400 is standing in position 3 a circuit is closed from battery, resistance 495-14, contact of cam 48GA to conductor 521. T his circuit extends over the contact ot key 120, through the winding of relay 121, and when interrupter 122 closes its lower contact to gro-und over the interrupter. Relay 121 is marginal and will not operate in series with resistance 495-11. 1f link B should be hunting for an idle position and have its sequence switch standing in position 3 also, it will connect battery to conductor 521 through resistance 495-13 in parallel with resistance 495-A- The resistance in series with the relay 121 under these circumstances will be one-halt what it was when link A alone was limiting. Similarly, it links A, B and C should all hunt sin'iu'ltaneausly, the resistance in series with relay 121 would be one-third that of a single link. In the system on which the present disclosure is based, relay 121 is so adjusted that it will operate only it four links simultaneously stand in position 3 and the resistance in series with it is one-fourth that of a single link.

Assume that such a condition has arisen and that relay 121 operated at the elo-sure of the lower Contact ot interrnpter 122. Very shortly after interrupter 122 closes its lower contact, it closes both its upper and lower contacts, completing a circuit from ground over the interrupter contacts, front contact of relay 121, winding of relay 124, resistance lee 123 to battery. Relay 124 locks over its inner left contact to ground. After a short measured interval interrupter 122 first opens the circuit of relay 124 and then that of relay 121. Relay 121 releases, but relay 124 remains locked. Approximately two seconds later interruptor 122 recloses its lower contact. lf relay 121 is again operated at this closure, relay 124 remains operated. 1f, however, at this time-the number oi linlrs in position 3 is less than 4 and relay does not reoperate, a circuit is closed when the upper contact closes Jfrom ground, over the cont-acts of interrupter 122, baclr contact of relay 121, resistance 123 to battery, shunting relay 124 and causing it to release.

The operation of relay 124 connects ground over its outer contact to interrupter 125. 1i' the condition continues until interrupter 125 closes its lower contact, a circuit will be closed thereover to the winding of relay 126 and battery. Relay 126 locks over its right contact to the contact of relay 124. Approximately half a minute later, interruptor 125 closes its upper contact. It relay 124 has remained operated throughout that interval so that relay 126 also remains operated, a circuit is closed from battery, through the winding of relay 127, Contact of relay 126, upper contact of interrupter 125, to ground at the front contact of relay 124. Relay 127 also locks to the contact of relay 124. At its inner left contact relay 127 lights lamp 128 and at its outer left contact operates buzzer 129 over hey 130. The person in charge of the oiiice will then know that the number of operators7 positions occupied is inadequate for the trallic and may take steps to remedy'the condition. As soon as the condition ceases relay 121 fails to operate, relay 124 is shunted and released and the locking circuits of relays 126 and 127 are opened, extinguishing the lamp and silencinO' the buzzer. The buzzer may also be silenced by operating key 130.

The operation of key 132 connects resistance 133 in parallel with relay 121, thus increasing the margin oi that relay so that the number of calls required te operate the relay is increased. 1n the systemV upon which the'present disclosure is based the increase was from 4 to 7. The milliammeter 131 may be used to check the number of calls waiting where they are less than the number necessary to operate the alarm-or after the operation of the alarm to ascertain the actual number waiting. The resistances are so proportioned to the battery voltage as to. permit a now of .01 ampere for each circuit standing in position 3. For example, if the battery voltage is 50, resistance 495-A will be 5,000 ohms, and the current ow will be .01 ampere. 1f a second resistance, for eX- ample, 495-13, is connected in parallel therewith, the ellective resistance will be 2,500

ohms and the current ow will be .02 ampere, etc. 1f the current flow in-.this circuit becomes excessive the fuse 134 will open to operate buzzer 129. 1n that case, operating key 130 will fail to silence the buzzer and inf. dicate a ruse failure. It will be noted that the operation of relay S04-NL S04-N, etc., in any position due to the presence of an operator at that position connects ground over its middle contact to conductor 642, holding relay 110 operated." llhen an operator vacates her position, one operating ground igor relay 110 is removed. lOnly if all positions are vacated, which may occur during the night, is relay 110 released. Similarly, when position M is occupied andV idle, ground will be connected over the outer front Contact of relay 604-M, and the outer back contact of relay (SO2-M to conductor 643 holding relay 100 operated. As each posi-pV tion becomes busy, thecorresponding ground is disconnected from conductor 643 and if all positions become busy, relay 100 releases. Likewise it' -all positions become vacant, relay 100 releases. The release of relay 100V44 closes a circuit for relay 101 which operates, connecting ground over the winding oit' relay '111 to conductors 520-A, 52013 and so on.

1f, now, a call is extended to a trunk at this ofce, assuming that link A is used, sequence switch 400 advances to position 2 in the usual manner. As soon as it reaches position 2, a circuit is closed from battery, through resistance 519, winding of relay 509,

contact of cam 487-A, conductor 520-A,

front contact of relay 101, winding of relay 111 to ground. Relays 111 and 509 operate in this circuit and relay 509 removes ground from the circuit oi" relay 50;7 preventing the position iinder from hunting until there is an idle position to be found. 1f relay 110 is also released, because all positions are vacant rather than busy, a circuit is closed from ground over the back contact of relay 110, front contact of relay 111 to ringer 112 and a source of ringing current, to warn the attendant that a call is awaiting attention. The operator may then insert her telephone in any convenient position jaclr, operating relays 100 and 110, silencing the ringer, releasing relay 509 and permitting the position finder 500' to extend the connection to her position.

It will be apparentthat these circuits form a convenient and accurate check upon the efficiency of the service given.

What is claimed is:V

1. In an electrical system, a plurality of similar elements, means to cause said elements to assume a plurality oi diilerent conditions, a circuit closed under the control of each of said elements when in a predetermined condition, and means responsive to the simultaneous closure of said circuit by a predetermined number of said elements to sound an alarm. l

2. In an electrical system, a plurality of circuit elements, means tc operate each element through a plurality of different stages, means to indicate when each of said elements passes through a particular stage and means tor sounding an alarm when a predete 'mined number of said indications occur simultaneously.

23. In an electrical system, a plurality et switches, means to operate each of said switches through a plurality of positions, means to indicate when each of said switches is in a particular position and means for sounding an alarm when a predetermined number of said switches are simultaneously in the same position.

4. In a switching system, a plurality of hunting switches, a plurality of elements accessible to said switches, means to mark said elements as selectable or non-selectable, means to cause said switches to hunt for a selectable element, and means to indicate when a predetermined number of said switches are hunting for selectable elements at the same time.

5. In a switching system, a plurality oi limiting switches, a plurality of elements ac cessible to said switches, means to mark said elements as selectable or non-selectable, means to cause said switches to hunt for a selectable element, and means responsive when a predetermined number ot said switches hunt tor selectable elements simultaneously for more than a predetermined length of time to sound an alarm.

6. In a switching system, a plurality of hunting switches, a plurality of elements accessible to said switches, means to mark said elements as select-able or non-selectable,m.eans to cause said switches to hun? for a selectable element, means responsive when a predetermined number of said switches hunt for selectable elements simultaneously for more than a predetermined length of time to sound an alarm, and means to render said alarm responsive when a different predetermined number of said switches hunt simultaneously.

7. In a switching system, a plurality of hunting switches, a plurality of elements accessible to said switches, means to mark said elements as selectable or non-selectable, means to cause said switches to hunt for a selectable element, an alarm, and means to sound said alarm when a predetermined number of said switches are hunting for selectable elements at the same time comprising a. marginal relay, an interrupter and a. circuit for said re- 'lay controlled by said switches and said interrupter.

8. In a switching system, a plurality of limiting switches, a plurality of elements accessible to said switches, means to mark said elements as selectable or non-selcctablenneans to cause said switches to hunt for a selectable element, an alarm, and means responsive when a predetermined number of said switches hunt for selectable elements simultaneously for more than a predetermined length of time to sound said ala m, comprising a` marginal relay, a first interrupter, circuits for said relay controlled by said switches and said interrupter, a second in-l terrupter, and a circuit for said alarm controlled by said marginal relay and said second interrupter.

9. In an electrical system, a plurality of elements each having a plurality of possible conditions, and means for sounding an alarm when a predetermined number of said elements are simultaneously in the same predetermined condition comprising a marginal relay operable through a resistance of not more than a predetermined value, parallel circuits for said relay each containing a resistance having a value which is a multiple of said predetermined value closed by said elements when in said predetermined condition and an alarm responsive to said marginal relay.

l0. In an electrical system, a plurality of elements each having a plurality ot possible conditions, a marginal relay operable only through a resistance of not more than a predetermined value, parallel circuits for said relay extending to each ot said elements, a resistance individual to each element of a value which is a multiple of said predetermined value, means in each element to connect said resistance in series with said relay over one of said parallel circuits when said element is in a predetermined condition, and means to complete the circuit of said relay, said means being effective to operate said relay only if a suliicient number of said elements are in said predetermined condition to reduce the resistance in series with said relay below said predetermined value.

11. In a telephone system, a plurality of link circuits, a plurality of operators positions, means responsive to the extension of calls to said link circuits to cause said link circuits to hunt for operators positions, means to render said operators positions non-selectable when busy or vacant, a sequence switch associated with each link circuit, means eective to hold said sequence switch in a particular position until an idle operators position has been found, and means effective if more than a predetermined nulnber of said sequence switches are simultaneously in said particular position to sound an alarm.

1Q. In a switching system, a plurality of hunting switches, a plurality ot elements accessible to said switches, means to mark said elements as selectable or non-selectable, means to cause said switches to hunt for a selectable element, an alarm, and means responsive when a predetermined number of said switches hunt for selectable elements simultaneously for more than a predetermined length of time to sound said alarm, comprising a marginal relay, parallel circuits i'or said relay, each controlled by one ot' said switches and each containing a predetermined resistance, and an interrupter tor completing the circuit of said relay.

13. In a switching system, a plurality of hunting switches, a plurality of elements accessible to said switches, means to mark said elements as selectable or non-selectable, means to cause said switches to hunt for a selectable element, an alarm, and means to sound said alarm when a predetermined number of said switches are hunting for selectable elements at the same time comprising a marginal relay, an interrupter, circuits for said relay controlled by said switches and said interrupter, and means to render said alarm responsive when a different predetermined number of said switches hunt simultaneously.

lll. ln a telephone system, a plurality of link circuits, a plurality of operators positions, means responsive to the extension of calls to said link circuits to cause said link circuits to hunt for operators positions, means to render said operators positions non-selectable when busy or vacant, a sequence switch associated with each link circuit, means edective to hold said sequence switch in a particular position until an idle operatorls position has been found, and means eieotive if more than a predetermined number o said sequence switches are simultaneously in said particular position to sound an alarm, said means comprising resistances connected by each ot' said sequence switches in parallel with each other anda relay in series with said resistances operable only through said predetermined number 01"' resistances.

l5. In a telephone system, a plurality oi' link circuits, a plurality of operatorsl positions, means responsive to the extension of calls to said link circuits to cause said link circuits to hunt for operators positions, means to render said operators positions non-selectable when busy or vacant, a sequence switch associated with each link circuit, means eiective to hold said sequence switch in a particular position until an idle operators position has been found, and

' means effective if more than a predetermined number or said sequence switches are simultaneously in said particular position to sound an alarm, said means comprising resistances connected by each or" said sequence switches in parallel with each other and a relay in series with said resistances operable only through said predetermined number of resistances, and means to render said alarm ef- Yiective when a dierent predetermined number of said sequence switches are simultaneously in said particular position comprising a key-controlled shunt for said rela 16. ln a switching system, a plurality of hunting switches, a plurality of elements accessible to said switches, means to mark said elements as selectable or non-selectable, means to cause said switches to hunt for a selectable element, an alarm, and means to sound said alarm when a predetermined number of said switches are hunting for selectable elements at the same time comprising a marginal relay, an interrupter, circuits .for said relay controlled by said switches and said interrupter, and means to render said alarml responsive when a different predetermined number of said switches hunt simultaneously comprising a key-controlled shunt for said relay.

, i7. ln a switching system, a plurality of uniting switches, a plurality of elements acessible to said switches, means to mark said elements as selectable or non-selectable, means to operate each of said switches to hunt for a selectable element, means to disable said operating means if all of said elements are non-selectable, and means to indicate when a predetermined number of said operating means are disabled. y

18. ln a switching system, a1 plurality of elements, means for marking said elements selectable or non-selectable, a switch, means to operate said switch to sel-ect one ot said elements, and means individual to said switch to disable said operating means if all oi said elements are noneselectable.

i9A in a telephone system, a plurality of operators positions, means to mark said positions as busy or idle, a switch for selecting an operators position, and means to operate said switch to hunt for an idle operators position, and means to disable said operating means if all of said positions are busy.

20. ln a telephone system, a plurality ot operators7 positions, means to mark said positions seleetable only when occupied and idle, a switch for selecting an operators position, means to operate said switch to hunt for a selectable position, means to disable said operating means, and means to operate said disabling means if all oi said positions are non-selectable, said last means being effective whether said positions are rendered nonselectable by being busy or by being unoc. cupied.

2l. In a telephone system, a link circuit, a finder switch individual to said link circuit, plurality of operators positions, means to mark said positions as busy or idle, means for operating said i'inder switch to hunt for an idle operators position, means to disable said operating means, and means to operate said disabling means if all of said positions are busy, said last means being eftective only during the time said operating means is eiiective.

22. In a telephone system, a link circuit, a sequence switch individual to said link cir cuit, a finder switch individual to said link circuit, a plurality of opera-tors positions, means to mark said positions as busy or idle, means effective in a particular position of said sequence switch to operate said finder switch to hunt for an idle operators position, means to disable said operating means, means to operate said disabling means if all of said positions are busy, said last means being effective only if said sequence switch is in said particular position. n

23. In a telephone system, a plurality of link circuits, a sequence switch individual to each link circuit, a plurality of operators positions, means to mark said positions as busy or idle, means effective in a particular position of each sequence switch to operate the corresponding finder switch to hunt for an idle operators position, means individual to each switch to disable said operating means, means to operate said disabling means if all of said operators positions are busy, said last means being effective on the disabling means of those linl; circuits only whose sequence switches are standing in said particular position.

In witness whereof, I hereunto subscribe my name this 7 th day of June, 1928.

RALPH E. HERSEY.

DISCLAIMER 1,792,538.Ralph E. Hersey, Brooklyn, N. Y. TELEPHONE SYSTEM. Patent dated February 17, 1931. Disclaimer iiled March 22, 1932, by the assignee, Bell Telephone Laboratories, Incorporated.

Hereby enters this disclaimer to the said claims of said Letters Patent which are in the following words to wit:

1. In an electrical system, a plurality of similar elements, means to cause said elements to assume a plurality of different conditions, a circuit closed under the control of each oi said elements when in a predetermined condition, and means responsive to the simultaneous closure of said circuit by a predetermined number of said elements to sound an alarm.

4. In a switching system, a plurality of hunting switches, a plurality of elements accessible to said switches, means to mark said elements as selectable or non-selectable, means. to cause said switches to hunt for a selectable element, and means to indicate when a predetermined number of said switches are hunting for selectable elements at the same time.

5. In a switching system, a plurality of hunting switches, a plurality of elements accessible to said switches, means to mark said elements as selectable or non-selectable, means to cause said switches to hunt for a selectable element, and means responsive when a predetermined number of said switches hunt for selectable elements simultaneously for more than a predetermined length of time to sound an alarm."

7. In a switching system, a plurality of hunting switches, a plurality of elements accessible to said switches, means to marl( said elements as selectable or non-selectable,

means to cause said switches to hunt for a selectable element, an alarm, and means to sound said alarm when a predetermined number of said switches are hunting for selectable elements at the same time comprising a marginal relay, an interrupter and a circut for said relay controlled by said switches and said interrupter.

8. ln a switching system, a plurality of hunting switches, a plurality of elements accessible to said switches, means to vmark said elements as selectable or non-selectable, means to cause said switches to hunt for a selectable element, an alarm, and means responsive when a predetermined number oi said switches hunt for selectable elements simultaneously for more than a predetermined length of time to sound said alarm, comprising a marginal relay, a iirst interrupter, circuits for said relay controlled by said switches and said interrupter, a second interrupter, and a circuit for said alarm controlled by said marginal relay and said second interrupter.

9. In an electrical system, a plurality of elements, each having a plurality of possible conditions, and means for sounding an alarm when a predetermined number of said elements are simultaneously in the same predetermined condition comprising a marginal relay operable through a resistance of not more than a predetermined value, parallel circuits for said relay each containing a resistance having a value which is a multiple of said predetermined value closed by said elements when in said predetermined condition and an alarm responsive to said marginal relay.7

18. In a switching system, a plurality of elements, means for marking said elements as selectable or non-selectable, a switch, means to operate said switch to select one of said elements, and means individual to said switch to disable said operating means if all of said elements are non-selectable.

[Oiclal Gazette April 12, 1.982.] 

